Density functional theory study on the mechanism of absorption of CO2 by the ionic liquid 1-butyl-3-methylimidazolium acetate. (1st June 2014)

• Record Type: Journal Article
• Authors: Yan-Fe, Chen; Yan-Hong, Cui; Dong-Shun, Deng; Ning, Ai; Long, Ye
• Is Part Of: Progress in reaction kinetics and mechanism. Volume 39:Number 2(2014)
• Page Start: 197
• Page End: 208
• Publication Date: 2014-06-01
• Subjects: Chemical kinetics -- Periodicals; 541.39405
• DOI: 10.3184/146867814X13981545064856
• Languages: English
• ISSNs: 1468-6783

Abstract

The absorption of CO2 on 1-butyl-3-methylimidazolium acetate ([Bmim] [Ac]) with different substituents are calculated systematically at the GGA/PW91 level. Three hydrogen bonds are formed between [Ac]− and the cations of 1-n-[Bmim][Ac] ([NBmim]+) and 1-tert-[Bmim][Ac] ([TBmim]+). The interaction between CO2 and [NBmim][Ac] via a C–O bond is much weaker than that with [TBmim][Ac] by its forming an O…O…C…C four-membered ring. The chemisorption of CO2 on the ion pair [NBmim][Ac] is much weaker than that on [TBmim][Ac], as indicated from an absorption energy analysis. The frontier molecular orbitals show the electron density overlap between absorbed CO2 and the [Ac]– in CO2 – [NBmim][Ac] is much weaker than that in [TBmim][Ac]. As a result, the chemisorption of CO2 on [NBmim][Ac] is much weaker than that on [TBmim][Ac]. Ionic liquids based on [NBmim]+ can be used repeatedly, and the adsorbed CO2 would be more easily desorbed.